Keratinases from Coriolopsis byrsina as an alternative for feather degradation: applications for cloth cleaning based on commercial detergent compatibility and for the production of collagen hydrolysate.

OBJECTIVES: Keratinases are proteolytic enzymes that emerge as an alternative for dealing with the disposal of chicken feathers. In this study, we aimed to investigate the keratin-degrading enzymes secreted by the fungus Coriolopsis byrsina and their partial biochemical characterization to adapt their use for keratin decomposition, detergent additive applications, and collagen degradation. RESULTS: We observed the secretion of different proteolytic enzymes that possessed caseinolytic activity that peaked at pH 7.0-9.0 and 60-70 °C and at pH 10.5 and 55-60 °C, and keratinolytic activity that reached a maximum at pH 7.0-7.5 and 40-55 ºC and at pH 9.0 and 55 °C. Keratinolytic activity was maintained at approximately 63% of residual activity for 1 h at 50 °C. The caseinolytic activity at pH 10.5 remains stable until 1 h at 50 °C, and this is in contrast to the activity at pH 8.5, where the residual activity was 50%. Caseinolytic activity was inhibited only by PMSF, while keratinolytic activity was inhibited by PMSF and EDTA. When investigating the application of C. byrsina peptidases as an additive to commercial detergent, we observed an egg stain removal performance that was similar to that demonstrated by the commercial detergent. CONCLUSIONS: Based on their activity and stability at alkaline pH, these enzymes appear to be attractive candidates for use in the detergent industry. Additionally, the collagenolytic activity of these enzymes potentially allows for their use in a wide array of industrial sectors that require collagenolytic enzymes, such as for the production of collagen hydrolysates from residues derived from the meat industry.

Citrobacter diversus-derived keratinases and their potential application as detergent-compatible cloth-cleaning agents.

Currently, poultry farming is one of the sectors that have a significant impact on the global economy. In recent years, there has been an increase in the production of broilers, inflicting this segment of the industry to generate tons of keratin due to huge disposal of chicken feathers. This points to the need to degrade these chicken feathers, as they have emerged as a major threat to the environment. Thus, in this study we aimed to identify keratinases that are produced by the bacterium Citrobacter diversus and further investigate the biochemical characteristics of these keratin-degrading enzymes. In a submerged medium, the bacterium was capable of degrading chicken feathers almost completely after 36 h of fermentation. We found a maximum caseinolytic activity at pH 9-10.5 and 50-55 °C, and keratinolytic activity at pH 8.5-9.5 and 50 °C. Thus, given its stability at higher temperatures, upon incubation of this enzyme extract for 1 h at 50 °C, it showed approximately 50% of the keratinolytic and 100% of the caseinolytic activity. Further, under pH stability for 48 h at 4 °C, the enzyme extract maintained greater residual activity in the pH range 6-8. Caseinolytic activity was inhibited by EDTA and PMSF, whereas the keratinolytic activity was inhibited only by EDTA. Additionally, due to its alkaline activity and detergent compatibility, this enzyme extract could improve washing performance when added to a commercial detergent formulation. Using application tests, we could demonstrate a potential use of this bacterial enzyme extract as an additive in detergents to remove egg stains from cloth.